Via RPLife Paulo Branco talked to Portugal's newspaper Correio da Manha about the 'Cosmopolis' Portuguese Premiere and said that the event will be on May 28 and there will also be a screening on May 29. Rob, Giamatti, Cronenberg and DeLillo will attend.
His TV interview mentioning the Portuguese promo was posted here

Translation via RPLife Link @veraleeon Thanks.
Guimarães – Capital Europeia da Cultura will have an unprecedented turnout on May 28, when the English actor Robert Pattinson, idol of millions of movie fans, will attend the premiere of 'Cosmopolis', directed by David Cronenberg and produced by Paulo Branco, days after learning if they won the Palme d'Or at the Cannes Film Festival.

Major flooding will certainly happen on May 29, in the two 'Cosmopolis' screenings in Lisbon. One will take place at Centro Cultural de Belém, while the other will be open to the public, and Pattinson (and other actors, including Paul Giamatti) will be with the fans. The 'team' also includes the filmmaker David Cronenberg and writer Don DeLillo, whose novel is the basis of the film.

"I hope the fans are more civilized here," said Paulo Baulo to the CM, acknowledging that Pattinson's stay in "Cannes is a concern," since his last time in the French city the reactions were described as Beatles-like.

In the film which opens in 30 theaters on May 31st, Pattinson plays a character very different from the vampire 'Edward Cullen', star of Twilight. This is the odyssey of a Manhattan mogul that runs through the city (although shooting has taken place in Toronto and not in New York) in his limousine.

'Cosmopolis' wants the Palme d'Or -'Cosmopolis' is in a list of candidates for the Palme d'Or in the official competition of the Cannes Film Festival, revealed yesterday. According to Paulo Branco, producer of the film where David Cronenberg has made a metaphor about the capitalism crisis, to find yourself in this list "will only provide visibility throughout the world" to the project. Besides the 11th film produced by Branco candidate for the top prize at Cannes, the festival which runs from May 16-27 features works by Walter Salles ("On the Road"), Leos Carax ("Holy Motors"), Michael Haneke ("Amour") and Wes Anderson, whose 'Moonrise Kingdom' opens an exhibition.